1. Field of the Invention
The present invention relates generally to the control and treatment of stormwater prior to discharge to localized infiltration zone soils. More particularly, the present invention relates to a system for diverting stormwater through compacted soil fill material to the infiltration zone soils.
2. Description of the Prior Art
Stormwater is rainwater that when falling on a developed environment will most often collect contaminants from the built surfaces and subsequently carry these unwanted contaminants to streams and lakes. Controlling stormwater runoff from a developed property has traditionally involved the use of systems of catch basins and pipes to catch and convey the water to centralized areas for storage and or treatment prior to discharging to either the ground or to a downstream surface water body. Although the main goals for using these traditional stormwater control systems is the prevention of flooding of downstream properties, reducing erosion of creeks and attempting to maintain water quality, the level of success in meeting these goals has been questioned.
Relatively recently, the idea that not focusing the stormwater to centralized storage and treatment areas, but instead treating and discharging the stormwater nearer to where it falls from the sky is gaining support. These new ideas and the associated techniques to implement these ideas are today called Low Impact Development (LID).
The use of porous pavement and related surfaces is one of these LID techniques that has gained acceptance as a storm control system. An alternative to catching and focusing rainwater toward centralized areas, the use of porous surfaces allows the water to soak into the existing soils approximately at the same location where the raindrop first hits the ground surface. The intent is that the water does not runoff the developed surfaces and therefore is not focused to centralized areas. The rainwater instead continues to follow the same approximate subsurface flow path after development as it did prior to development. This same idea can be achieved using traditional impermeable surfaces if multiple inlets are placed throughout the surface in a manner not generally recognized in current design technology.
At this time given the current technology, a significant limitation to these practices associated with the use of these porous surfaces for stormwater control purposes exists. In areas where compacted soil fill embankments are required based on existing topographic and/or other conditions, the use of porous surfaces may not be compatible. This is due to the fact that a compacted soil fill embankment that is constructed between the built porous surface and the existing ground soils essentially blocks the hydraulic connection between these surfaces and thus inhibits the water from traveling vertically downward as needed. On this basis, it is currently recognized that porous pavements sections and related surfaces should not be constructed over significant compacted soil fill embankment areas. Therefore, the current invention is needed.
Another recognized problem associated with the stormwater contacting the built surfaces is water quality degradation. Therefore, prior to allowing discharge of the water to native soils for infiltration or discharge to downstream water bodies it must be treated or filtered. Traditionally the use of centralized storage and treatment facilities has complicated this issue more as higher flows must be treated. In addition, filter systems presently used are centralized substantial structures. They include a plurality of individual filter assemblies in one or a very few common locations for a large developed property, for example. The failure or blockage of just a few of the assemblies, as well as regular maintenance, requires the shutdown of the centralized system, thereby exposing a substantial portion of the developed property to the generation of untreated stormwater.
What is needed is a stormwater control system suitable for use with pervious built surfaces or impervious built surfaces located over compacted fill material including, but not limited to, soil fill material. What is also needed is such a control system that transfers the stormwater to underlying local native infiltration zone soils. Further, what is needed is such a system that may also include a filter device that is localized rather than centralized.